1. Field
The present application relates to a magnetic tape driving apparatus capable of driving a magnetic tape, and a magnetic tape driving method. In particular, the present application is useful for a magnetic tape apparatus that uses a magnetic sensor head to linearly record data on a magnetic tape with a surface smoothness Ra of 3.0 nm or less.
2. Description of Related Art
A magnetic tape is a kind of magnetic recording medium and for various applications such as an audio tape, a video tape, and a computer tape. Particularly, in the field of backup tapes for computers, tapes with a storage capacity of hundreds of gigabytes per volume have been commercialized along with an increase in capacity of a hard disk to be backed up. In the future, backup tapes with a larger capacity are essential to deal with a further increase in capacity of the hard disk.
For a magnetic tape used as a backup tape, the recording wavelength becomes shorter as the recording capacity increases further, and the surface smoothness has been improved to suppress the degradation of recording/reproducing characteristics due to spacing. When the surface of the magnetic tape is smoothed, the contact area between the magnetic tape and a magnetic head is increased, thus increasing friction between them. Particularly, static friction occurs, e.g., at the time the magnetic tape that is in contact with the magnetic head starts running. If this static friction is increased, the magnetic tape and the magnetic head may be damaged. In order to address such static friction between the magnetic head and the magnetic tape, e.g., JP 2006-127666 A and JP 2008-262645 A disclose the following technology.
In JP 2006-127666 A, small recesses are formed in a BOT (beginning of tape) portion and an EOT (end of tape) portion so as to reduce static friction between the magnetic tape and the magnetic head during magnetic recording and reproduction. With this configuration, even if the magnetic tape starts running while the magnetic head is positioned at the BOT portion or the EOT portion, tape damage can be suppressed because of reduced static friction.
JP 2008-262645 A discloses a recording and playback device that includes a speed detector for detecting a running speed of a magnetic tape, a rocking apparatus for vibrating a magnetic head, and a controller for making the magnetic head vibrate by the rocking apparatus when the running speed of the magnetic tape is decided to be lower than a predetermined value, while making an operation of the rocking apparatus stop when the running speed is decided to be at least the predetermined value. With this configuration, static friction between the magnetic head and the magnetic tape is suppressed.
However, in the configuration of JP 2006-127666 A, the recesses are formed only in the BOT portion and EOT portion of the magnetic tape. Therefore, when the start and stop motions of the magnetic tape are repeated with the magnetic head being in contact with the portion (in which no recess is formed) between the BOT and EOT portions, the magnetic head or the magnetic tape are damaged by the static friction between them.
In the configuration of JP 2008-262645 A, a speed detector for detecting the speed of the magnetic tape and in particular, a rocking apparatus as a component essential for the configuration are required, resulting in a problem that the device is upsized and the cost for producing the device is increased.
It is an object of the present application to provide a magnetic tape driving apparatus that does not suffer from damage to a magnetic head and a magnetic tape when the magnetic tape makes a transition from the stopped state to the running state and vice versa or reverses in the running direction of the magnetic tape, and that can prevent damage to the magnetic tape and the magnetic head.